The most important thing when preparing for a sale is to make
It is very hard to sell a business that is totally dependant on you working a 60 hour week. Who wants to pay good money for a life like that?
In particular, start banking all the money, even if it means paying tax, and write up your closing stock and work-in-progress to full value.
Next is the question of perceived risk for the buyer. The lower the risk, the higher the price.
So the more you can do to instil confidence in the buyer, the better.
You can do this with documentation – document your sales, your supply agreements with suppliers and customers, your procedures etc etc.